About MBR and GPT partition styles
There are two partition styles of disk: MBR (master boot record) or GPT (GUID partition table). A new hard drive cannot be used to save data directly. It should be initialized to either MBR or GPT partition styles before using. However, what if you need a GPT disk while it is MBR? Fortunately, you can convert MBR disk to GPT disk in some ways.
MBR disk uses the standard BIOS partition table. On a MBR disk, you can create up to 4 primary partitions. If you need more partitions, you can change one primary partition to an extended partition so that you can create more logical partitions for use. Moreover, MBR disk supports up to 2TB storage space, which is why some users met the problem like 3TB hard drive only showing 2TB in Disk Management.
GPT disk uses the standard UEFI (unified extensible firmware interface) partition table. You can create up to 128 primary partitions on a GPT disk. And a GPT disk can recognize up to 18EB. But using GPT disk requires your computer’s motherboard supports EFI firmware. If there is no such support, you may boot Windows failure.
Why you need to convert boot disk between MBR and GPT style?
Imaging that your boot disk is a MBR disk, and you already have created 4 primary partitions on the disk, but you need more primary partitions. How could you do? For this situation, to convert boot disk from MBR to GPT partition style is a good solution. But if your Windows cannot be installed to GPT style partition because the computer does not support EFI firmware, convert boot disk from GPT to MBR partition style is a good solution. But how to convert boot disk between MBR and GPT partition style without reinstalling the OS?
How to change boot disk between MBR and GPT styles without reinstalling system?
Changing disk between MBR and GPT styles is a good solution for those questions we mentioned above. But how to convert boot disk between MBR and GPT style? Can the disk boot normally after conversion? Here, we will give you a safe way to convert boot disk between MBR and GPT without losing data. That is using the partition tool AOMEI Partition Assistant Professional to change boot disk between MBR and GPT.
Convert system disk from GPT to MBR partition style
If you are trying to use Windows Disk Management to convert GPT disk installed system, the Convert to MBR Disk option would be greyed out so that you have no idea for how to do it. But with the help of AOMEI Partition Assistant Professional, convert system disk from GPT to MBR partition style would be a simple thing.
Although this operation will not losing any data, you still need to backup disk first to prevent any accident that cause data lose.
1>. Launch Partition Assistant, you will see the basic environment of your hard drive(s). Here you can see your GPT disk with system partition on. To convert boot disk from GPT to MBR, here you need to right click the disk, select Convert to MBR.
2>. Then, you will move to a window where you should confirm the operations. Click OK.
3>. Then, you will back to the main interface. And you can see the GPT disk has already changed into MBR. Click Apply.
4>.Then, it will execute the task immediately. When the progress done, it will remind you that the operation has been complete successfully, now please reboot the computer for the operation to take effort. Click OK to reboot by changing boot order to BIOS mode.
Convert system disk from MBR to GPT partition style
Actually, changing the MBR disk with Windows OS stored on to GPT may lead to boot failure. Because booting Windows from MBR disk employs Legacy BIOS mode while booting from GPT disk employs UEFI mode. What’s more, the Windows 32 bit cannot be installed on a GPT disk. It seems like a very terrible job. So, if you are planning to convert system disk from MBR to GPT style, you need to check whether your computer supports UEFI mode. If it does, you can launch AOMEI Partition Assistant Professional to convert system disk from MBR to GPT partition style.
Backup disk before conversion to keep your data safe.
1>. Right click the MBR disk installed on Windows OS. Select Convert to GPT Disk.
2>.Then, it will still pop up a windows to ask if you are sure to convert MBR disk to GPT.
After click OK, it will give you a warning that you should make sure if your motherboard supports EFI/UEFI boot. If not, your system will be unable to boot next time. Click Yes.
3>. After that, you will back to the main interface. And you can see that the MBR disk has already changed into GPT. Click Apply.
4>. Click Proceed.
5>. The program may pop out a window if there is any partition being used by other programs, and you need to choose an option to execute the progress. Here choose Retry.
Then, click Yes to confirm.
6>. Wait till the program finish. And reboot your computer from EFI/UEFI firmware.
AOMEI Partition Assistant is such a great disk manager. You can use it to convert boot disk between MBR and GPT partition styles easily as the operation above, and you can convert MBR GPT easier. Besides, it supports you to convert disk types between basic disk and dynamic disk, change partition types between primary partition and logical partition, and convert between FAT32 and NTFS without losing data, and many other features. What's more, AOMEI Partition Assistant Professional supports all Windows PC OSes including Windows 10/8.1/8/7/Vista/XP. If you are Windows Server users, the AOMEI Partition Assistant Server is suitable for you.